The present invention relates generally to low profile surface mounted magnetic components and, more particularly, to magnetic components which include windings defined by a folded sheet material blank. The invention further relates to a multiple output switching power supply incorporating such components.
Surface mounted magnetic components such as inductors and transformers have typically been constructed using conductive wire having a circular cross-section wound around a ferrite core. Components constructed in this manner are quite large relative to other surface mounted components, particularly in the height dimension, due to the large number of windings required and because of the size of the ferrite core. This is particularly the case in high power applications where it is necessary to use large diameter wire. Such components also generate a substantial amount of heat due to conductive loses which occur as a result of the large number of windings typically required for these components.
More recently, magnetic components having planar windings etched in a spiral format on a printed circuit board have been utilized. These components are compact and have a low profile due to the planar etched windings. However, the etched windings do not provide sufficient current carrying capability for high power applications.
Magnetic components including a plurality of stamped windings are known in the art. Due to the higher volume of copper provided by the stamped windings, such components are more suitable than components having etched windings for high power applications and are therefore useful in devices such as high current switching power supplies. However, each of the stamped windings must be individually connected by a lead frame to an associated connection pad on the PC board. The substantial number of solder connections that are required makes assembly devices including such components both difficult and time consuming and also raises concerns regarding the reliability of these devices.
Accordingly, there is a need for low profile magnetic components which provide sufficient current carrying capability for high power applications and which have low leakage inductance, low conductive loses and reduced heat output. There is also a need for devices, such as switching power supplies, incorporating such components which having improved reliability and repeatability in manufacturing.